The code is supposed to follow somehow what the comment above says, that
is to have one channel with a wave of freq 440 and the other channel
with a wave of freq 880, but an off by one error results in frequencies
of 0 and 440.
https://bugzilla.gnome.org/show_bug.cgi?id=735673
wavenc only accepts little-endian PCM, but most of our
elements such as audiotestsrc only produce or process
audio in native endianness, so we need to plug a
converter before wavenc on big endian systems.
